1. Field of the Invention
The present invention relates to a cyst puncture catheter assembly including a catheter and a stylet wherein the catheter and stylet are inserted into a cyst together without relative movement (telescoping) between the catheter and the needle.
2. Description of the Related Art Including Information Disclosed under 37 C.F.R. .sctn..sctn.1.97-1.99
Heretofore, combination cyst puncture stylets and drainage catheters that are inserted into cysts have suffered from the problem of telescoping of the catheter on the stylet when the stylet is inserted into a cyst.
Also, there is a problem in that some cysts can be pierced with a rounded end stylet and other cysts made of a tougher or harder tissue can only be punctured with a pointed end stylet.
In other words, a number of cystic lesions cannot be treated with standard ventricular catheters, as they either have walls too tough to be penetrated by a blunt-ended catheter needle or because they are relatively mobile and are displaced by the catheter rather than punctured by it.
Tough wall cysts may eventually be punctured by a fine sharp biopsy needle but subsequent catheter placement is often difficult or impossible because of drainage of the cyst contents or inability to enter the same hole in the cyst wall with the catheter.
One previously proposed approach to inserting a catheter into a cyst is to first insert a cannula with a sharpened end into the cyst followed by inserting a catheter through the cannula into the cyst. Such a catheter device is disclosed in the Knoepffler U.S. Pat. No. 5,176,647.
A similar structure including a puncture tube that receives a drainage tube therein is disclosed in the Akiyama U.S. Pat. No. 3,896,810.